Means for supporting electrodes in ionic tubes



C. H. HARVEY. MEANS FOR SUPPORTING ELECTRODES IN IONIC TUBES. APPLICATION FILED MAY 7, 1918.

Patented Aug. 30, 1921.

\AWAMW um 31M Wm 3W the difficulty by mrreo STATES PATENT OFFICE;

CHARLES HOWARD HARVEY, OF LONDON, ENGLAND, ASSIGNOR, BY MESNE ASSIGN- MEN TS, TO THE GENERAL ELECTRIC COMPANY, LTD., 01 LONDON, ENGLAND.

MEANS FOR SUPPORTING ELECTRODES IN IONIC TUBES.

' Specification of Letters Patent.

Patented Aug. 30, 1921.

Application filed May 7, 1918. Serial No. 232,999.

To all whom it may concern Be it known that I, CHARLES HOWARD HARVEY, a subject of the King of Great Britain, residing at London, England, have invented new'and useful Means for Supportin vElectrodes in Ionic Tubes, of which the following is aspecification.

This invention relates to ionic tubes, more particularly such as are used as transmitting or receiving valves in wireless telegraphy, having a looped cathode-filament whereof the loop or bight is elastically supported by means of a coiled spring the axis of which extends in substantial alinement with the filament, the spring being attached on the one hand to the bight of the filament and on the other hand to a hookedwire or like member which extends in substantial alinement with the filament and spring-axis and is sealed or fused into the glass of the bulb or of some part integral with or mounted within the bulb, With such a construction,

and more especially in cases where the cathode-filament carries a heavy current, ex pansion, under heat, of the wire by which the filament-spring is anchored is liable to crack the glass into which saidwire is fused. The object of this invention .is to overcome providing such an anchorage for the anchor-wire that the latter, while remaining correctly alined, will be free to expand without any risk of thereby setting up disruptive strains in the glass with which itis in contact.

According to the present invention the anchor-wire, instead of being fused into the glass, is loosely but slidably supported in a stationary guide and is enlarged at its outer end so as to be adapted to engage, under the stress of the spring, with a stationary abut ment; the arrangement being such that the wire, while securely held not only againstthe stress of the spring but also against any tendency to lateral displacement beyond small limits, will nevertheless be free to expand, under the influence of heat, all directions without imposing any disruptive strain upon the glass with which it is in contact.

A convenient construction embodying the invention is illustrated in the accompanying drawing, which shows, in side elevation, one

the adjacent neck of the bulb; the loop of the cathode-filament and the improved anchorof an ionic tube and ing-means therefor bein shown, while the other members required to complete the structure of the tube as a whole are omitted.

On reference to the drawing it will be seen that the anchor-wire a, whereof the inner end is attached at b to a spiral spring 0 which is hooked at d to the bight of the looped cathode-filament e, has formed upon its outer end a knob f resembling a common pin-head; and that portion of the anchor-wire a which is adjacent to the knob f passes freely through a. short tubular socket g of glass, which is fixed in position within the bulb h and formed at its outer end with an enlargement j constituting a cavity for the accommodation of the knob f. This knob, being of larger diameter than the socket g, engages the shoulder presented by the outer end of the socket and thus prevents the retraction of the anchor-wire a under the contractile stress of the filament-spring a; while the anchor? wire a and knob f, being loose in the socket g and cavity 7', are free to expand under the influence of heat without imposing any disruptive strain upon the glass wherein they will be observed that the length and diameter of the tubular socket g are made such (relatively to the diameter of the, anchor-wire a) as to prevent the occurrence of more than a very small lateral canting of the anchorwire asthe result of the looseness of the wire in the socket, so that such looseness will not affect the steadiness with which the loop of the cathode-filament e is held in position.

In the example illustrated,; the socket g and its enlargement j are formed integrally with, or fused at 70 onto the closed inner end of a glass tube Z which extends through the neck m of-the bulb 7a, and in axial alinement with said neck and with the socket g; the tube Z, which is-reentrant with reference tothe neck m, being sealed by its open outer end into. the neck at hermeticclosure for the bulb. It will be obvious, however, that the socket g and its enlargement j might be supported within the bulb h or neck m by other means.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that whatI claim is 1. In an ionic tube, the combination of a looped cathode-filament, a coil spring having its one end attached to said looped filament,

nso as to constitute a" an anchor wire connected with the other end of said spring, said wire and the aXiS of said spring both extending in substantial alinement with said filament, an enlargement at the-outer end of said wire, a guide in said tube in which said anchor-wire is slidably mounted and loosely held against lateral displacement beyond small limits, and a stationary abutment in said tube for engagement by said enlargement whereby said anchor-wire is held against the stress of said filament spring, said anchor-Wire being free to expand in all directions without imposing any disruptive strains upon the guide and abutment. f

2. In an ionic tube, the combination of a tubular socket of glass fixed within said ionic tube, a shoulder at the outer end of said socket, an anchor-wire passing through said socket and slidable therein, a knob on the anchor-wire engaging saidshoulder, a filament and a sprin having its one end connected withsaid' end connected with said anchor-wire and exerting a stress whereby said knob is drawn against said shoulder.

3. In an ionic tube, the combination of a tubular socket of glass, a' hollow enlargement at the outer end of said socket forming a cavity, an anchor-wire passing through said socket and slidable therein, a knob on said anchor-wire for resisting its passage through said socket in one direction, said knob being accommodated within said cavity, a filament and a spring having its one end connected with said filament and its other end connected withsaid anchor-wire.

CHARLES HOWARD HARVEY.

filament and its other 

